Posterior Palatal Seal: Denture Retention

By Dr.Swathi Pai on Friday 9 January 2009 with 0 comments



I. Introduction

Complete dentures may suffer from a lack of proper border extension, but none are more important than the posterior limit and the posterior palatal seal on maxillary complete dentures. The posterior border is terminated on a surface that continues and is movable in varying degrees and not at a turn of tissue as are the other denture borders.

Deficiencies of the distal border may be in the length of the denture base, or the depth of the posterior palatal seal or both. These errors may lead to inadequate retention due to the lack of peripheral seal. (Millsap 1964).

The purpose of this seminar is to discuss the factors associated with complete denture retention, the importance of the posterior palatal seal, its location, design, placement of and processing influence.

II. Historical review

1883: Ames and the Greene brothers introduced atmospheric pressure as a means of denture retention and recommended the use of functional denture borders as opposed to passive borders in the fabrication of complete dentures.

1886: Wilson described adhesion as the primary determinant in denture retention.

1907: Green brothers " Modeling compound"

1920: Hall revived interest in the use of atmospheric pressure as a retentive factor by interpreting and demonstrating the functional denture borders.

1948: Stanitz used a lab model to suggest that atmospheric pressure is in equilibrium with fluid pressure exerted on molecules within a capillary tube with a liquid level in a container as well as the attraction of two glass slabs. These models explained how fluid film contributed to denture retention.

1951: Craddock described the gripping action of the buccinator muscle on the buccal flange of the mandibular denture and also coined the term "pear shaped pad".

1962: Stamoulis believed that atmospheric pressure combined with intimate tissue contact and peripheral seal comprise the most critical retentive forces.

1964: Fish discussed determinants of retention and differentiated between tissue, polished, and occlusal surfaces and how each permits the dentist to incorporate mechanical, biologic, and physical factors of the denture retention.

Category: Prosthodontics Notes

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